for (p = opt->header_list; p; p = p->next) {
if (p->token != GREP_PATTERN_HEAD)
die("bug: a non-header pattern in grep header list.");
- if (p->field < 0 || GREP_HEADER_FIELD_MAX <= p->field)
+ if (p->field < GREP_HEADER_FIELD_MIN ||
+ GREP_HEADER_FIELD_MAX <= p->field)
die("bug: unknown header field %d", p->field);
compile_regexp(p, opt);
}